Electron tube



Jan. 1 l, 1949.

D. F. DRlESCHMAN EX' Al.

ELECTRON TUBE Filed Jan. 25, 1346 INVENTORS Dona/a E Drieschman ATTORN EY Pat-nad im. 11, '1949 ELEc'raoN TUBE Donald F. Drieachnian, Los Altos, and Radford Leonard, San Bruno, Calif., assignors to Eitel- McCullough, Inc., San Bruno, Calif., a corporation of California Aipucauon January 2s, 194s, semi No. 643,286

' 1o claims. (ci. 25o-21.5,)

Our invention relates'to an electron tube ofthe type having parallel plane electrodes', and more particularly to improvements in the `tube structure disclosed in the application of Donald F. Drieschman, Serial No. 592,542, now Patent No. 2,446,269, filed May 8, 1945.

It is among the objects of our invention to provide a tube structure and method of assembling the same, wherebythe electrodes may be positioned with great accuracy and facility.

Another object is to provide a tube of the character described in which very close electrode spacings may be obtained, without special operator skill, and with the maintenance 'of uniform electrode spacings from tube to tube.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of our invention. It is to be understood that we do not limit ourselves to this disclosure of species of our invention as we may adopt variant embodiments thereof within the scope of the claims. n v

Referring to the drawing, the single figure of the drawing is an axial sectional view of a tube embodying the improvements of our invention.

In terms of broad inclusion, our improved tube comprises an envelope and electrode supports insertable in the envelope, the envelope and supports being shaped and proportioned to provide limit stops to establish predetermined spacing between the electrodes. Inour preferred structure the electrode supports comprise sleeves insertable in a tubular end section of the envelope, the sleeves being sized to nest together and into the tubular section so as to establish the desired electrode spacings when so nested. For a triode structure we prefer to carry the grid and cathode on the supporting sleeves and the anode on the opposite end of the envelope.

In greater detail, and referring to the drawing, our improvements are illustrated by a triode structure comprising an anode 2, grid 3 and cathode 4 arranged with active surfaces disposed in parallel planes. These electrodes are mounted in a suitable envelope comprising a body section 6 of vitreous material, such as glass, sealed at one end to an anode supporting member 1 and at the other end to a tubular envelope section 8. Anode support 1 also functions as the anode terminal and comprises a metal cup -having a cylindrical wall 9 extending from `a flange II to which the glass is sealed. Anode 2 is secured to neck I2 of the support .by braze I3.

The anode is preferably of metal havinggood 2 heat conductivity, such as copper, with a flat anode surface presented interiorly of the envelope and having a stem portion I4 extending outwardly of the envelope. A suitable cooler is provided on the anode, preferably comprising a metal core I6 fitted on stem I4 and carrying a series of transverse disk-like heat radiating ns I1 separated by spacing rings I8, the f-lns and spacers being clamped together by a crimped lip i9 on core I6.

The tube is exhausted through a metal tubulation 2I secured to anode stem I4 by braze I5 and communicating with a passage 22 ported into the envelope through opening 23. After exhaust, the tibcis sealed by pinching oil? the tubulation at t p Envelope section 8 at the opposite end of the envelope is a cylindrically shaped metallic member having an outturned flange 26 to which glass body section 6 is sealed. Section 8 is arranged coaxially with the anode and also functions as the terminal for g-rid 3. During assembly, the outer end of tubular section 8 is open, whereby the grid and cathode structures may be inserted through this end of the envelope.

Grid 3 is supported on a sleeve 21 of metal having good heat conductivity, such as copper, insertable in envelope section 8. The section 8 and sleeve 28 are shaped and proportioned to provide limit stops to establish a predetermined spacing between the grid and anode. This is preferably accomplished by an offset portion 29 on section 8 providing an annular seat engagable by a lip formed by an offset portion 3| on sleeve 21,

' Cathode 4 is mounted on a stem 32 also coaxial with the anode and arranged to project into the envelope through tubular section 8. The cathode stem comprises a pair of concentric stem mem- -bers including an outer tubular part 33 and an inner rod-like part 34. are joined together by a, glass bead 36 sealed between rod 84 and the lower end of a sleeve 31, which sleeve is fitted into stem member 33 and secured thereto by braze 38. For convenience in making connection with the inner stem member, a cup-shaped terminal 39 is preferably fixed to the outer end of rod 34 and spaced from the outer stem member by insulator 4I.

The cathode comprises a cylindrical can 42 having a at top carrying the active cathode coating which may be of the usual oxide type commonly used for indirectly heated cathodes. Can 42 is coaxial with and secured to the inner end of stem member 33. The cathode heater comprises a spiral 43 having one end connected.

These stem members l to stem member 34 by bracket 44 and the other end connected to stem member 33 by bracket 46. Suitable bailies 41 and 48 arranged in can 42 serve to conine the heat and direct it toward the active surface of the cathode.

The cathode structure is supported from envelope section 8 by a U-shaped metallic sleeve having an outer ilange 49 and an inner flange 5|,

-this cathode supporting sleeve being fitted into utilizing the folded inner end of the sleeve as a lip for engaging the seat provided by offset portion 3| of the grid supporting sleeve. The various parts are so proportioned that the distance between the upper grid surface and the lip at oiTset 3| is less than that between the anode surface and the seat at oiset 29 by the anode-grid spacing. Likewise, the distance between the cathode surface and the lip at the end of the cathode sleeve is less than that between the lower grid surface and the seat at oilset 3| by the gridcathode spacing. By this arrangement the electrodes are accurately and positively positioned with the desired electrode spacings. Tubes with an anode-grid spacing of .025 inch and a gridcathode spacing of .0045 inch have been satisfactorily made and used.

The nal closure is made by a fused metallic bond 56 joining the outer adjacent edges of.

section 8,sleeve 21 and sleeve iiange 49. This bond may be formed by welding or brazing to simultaneously join thethree edges together.

Our improved tube structure, above described, permits the electrodes to be assembled Within the envelope with great accuracy and facility, it requiring no special skill to nest the sleeves together and insert them into the envelope. Maintenance of precise spacings is positively assured by the limit stops on the nested parts. Another advantage of the structure is that the nal closure joint at 56 is made by a single fusing operation which simultaneously xes the parts together and closes the envelope.

While we have shown a triode structure to illustrate the invention, it is understood Ithat our improvements may be incorporated in tubes having additional electrodes. For example, a tetrode may be constructed with an additional supporting sleeve carrying a screen grid, thus making three sleeves nested together within envelope section 8.

We claim:

1. An electron tube having parallel plane electrodes, an envelope supporting an electrode at one end and having a tubular section at the other end, a pair of sleeves inserted in said tubular section and carrying others of said electrodes, one of said sleeves lying Within the other sleeve, said tubular section and said sleeves having limit stops to establish predetermined spacing between the electrodes.

2. An electron tube having parallel plane electrodes, an envelope supporting an electrode at one end and having a tubular section at the other end, a pair of sleeves inserted in said tubular section and carrying others of said electrodes,

one of said sleeves lying within the other sleeve. v

said tubular section and said sleeves having limit stops to establish predetermined spacing between the electrodes, and a fused bond joining adjacent edges of the tubular section and said sleeves.

3. An electron tube having parallel plane electrodes including an anode and grid and cathode, an envelope supporting the anode at one end and having a tubular section at the other end, a first sleeve inserted in said tubular section and carrying the grid, a second sleeve inserted in the rst sleeve and carrying the cathode, said tubular section and said sleeves having limit stops to establish predetermined spacing between the electrodes.

4. An electron tube having parallel plane electrodes including an anode and grid and cathode,` an envelope supporting the anode at one end and having a tubular section at the other end, a irst sleeve inserted in said tubular section and carrying the grid, a second sleeve inserted in the iirst sleeve and carrying the cathode, said tubular section and said sleeves having limit stops to establish predetermined spacing between the electrodes, and a fused bond joining adjacent edges of the tubular section and said sleeves.

5. An electron tube having parallel plane electrodes including an anode and grid and cathode, an envelope supporting the anode at one end and having a tubular section at the other end,

a seat on the envelope spaced from the anode, a grid support inserted in said tubular section and having a lip engaged with the seat on the envelope, the distance between the grid and its support lip being less than that between the anode and envelope seat by the `anode-grid spacing, a seat on the grid supportspaced from said grid, a cathode support inserted in the grid support and having a, lip engaged with the seat on the grid support, the distance between the cathode and its support lip being less than that between the gridj and its support seat by the gridcathode spacingi 6. An electrony tube having parallel plane electrodes, an envelope supporting an electrode at one end and having a tubular section at the other end, said section having an intermediate oiset portion, an electrode supporting sleeve inserted in the tubular section and having an intermediate offset portion engaged with the offset portion of said section, and another electrode supporting sleeve inserted in the rst sleeve and having an end engaged with the offset portion of said first sleeve.

7. An electron tube having parallel plane'electrodes, an envelope supporting an electrode at one end and having a tubular section at the other end, said section having an intermediate offset portion, an electrode supporting sleeve inserted in the tubular section and having an intermediate oiset portion engaged with the oiset portion of, said section, another electrode supporting sleeve inserted in the first sleeve and having an end engaged with the offset portion of said first sleeve, and a fused bond joining acljacent edges of the tubular section and said sleeves.

8. An electron tube having parallel plane electrodes including an anode and grid and cathode, an envelope supporting the anode at one end and having a tubular section at the other end, said section having an intermediate offset portion, a grid supporting sleeve inserted 5 in the tubular section and having an intermediate offset portion engaged with the oiset portion of said section, and a cathode supporting sleeve of U-shape inserted in the iirst sleeve and having a folded end engaged with the oiIset portion of said rst sleeve.

9. An electron tube having parallel plane electrodes including an anode and grid and cathode, an envelope supporting the anode at one end and having a tubular section at the other end, said section having an intermediate offset portion, a grid supporting sleeve inserted in the tubular section and having an intermediate offset portion engaged with the oiset portion of said section, a cathode supporting sleeve `of U- shape inserted in the first sleeve and having a folded end engaged-with the oiset portion of said iirst sleeve, a cathode stem, and a vitreous ring sealed between the stem and the inner ilange of said cathode supporting sleeve.

10. An electron tube having parallel plane electrodes including an anode and grid and cathode, an envelope supporting the anode at one end and having a tubular section at the other end. said section having an intermediate onset portion, a grid supporting sleeve inserted in the tubular section and having an intermediate oiset portion engaged with the offset portion of said REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,093,303 Beggs Sept. 14, 1937 2,262,901 Murphy Nov. 18, 1941 2,406,121 Young Aug. 20, 1946 2,406,850 Pierce Sept. 3, 1946 2,411,046 Liimatainen Nov. 12, 1946 

